<!DOCTYPE html>
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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>

</body>
<script>
    function delRepeat(arr) {
        let newArr = [];
        arr.forEach(function(item, index) {
            // 新数组.indexOf(旧数组中的值)
            if (newArr.indexOf(item) == -1) {
                newArr.push(item)
            }
        })
        return newArr;
    }

    let arr = [1, 1, 1, 8, 2, 3, 4, 5, 5, 3];
    console.log(delRepeat(arr));
</script>

</html>